Caffeine is a substance that is found in certain plants. It can also be man-made and added to foods. It is a central nervous system stimulant and a diuretic (substance that helps rid your body of fluids).

How does caffeine affect blood pressure?
Caffeine can cause a short, but dramatic increase in your blood pressure, even if you don't have high blood pressure. It's unclear what causes this spike in blood pressure.

Caffeine is a substance that exists naturally in certain plants. It can also be man-made and added to food products. It stimulates the central nervous system and is a diuretic, which means it increases urination.

Do you drink just one cup of coffee or tea first thing in the morning, hoping the caffeine in it will jump-start your day? Do you follow it up with a caffeinated beverage or two and then drink several more cups of coffee throughout the day?

Caffeine is a major  active compound in coffee and it is a mild brain stimulant. Caffeine is found in some 60 plant including
• Coffee beans
• Tea leaves
• Kola nuts, which are used to flavor soft drink colas

For nurses, drivers and others working the night shift, a cup of caffeine may do more than help them stay awake. According to a new study by Cochrane researchers, it may also help them avoid mistakes and improve their job performance, say researchers. This could mean fewer job-related accidents and injuries, although studies have yet to prove this.